Other than the common cold, back pain is the number one reason people visit a doctor in the United States. There are three principle sources of back pain: i) joint pain (40%); ii) pain from a nerve root (40%); and iii) disc pain (20%).
Spinal joint pain occurs in the facet joint between adjacent vertebrae. The five facet joints on each side of the lumbar spine produce pain signals when they become arthritic or because of injury due to trauma, with 90% of cases occurring at the L4/L5 and L5/S1 junctions.
Spinal fusion is a surgical procedure used to correct problems with the small bones in the spine (vertebrae). Adjacent vertebrae are fused together using bone paste so that they heal into a single, solid bone. A posterior lumbar interbody fusion (PLIF) involves adding bone graft to an area of the spine to set up a biological response that causes the bone to grow between the two vertebral elements and thereby preclude articulation at that segment. PLIF promotes spinal fusion by inserting a spacer, also referred to herein as an interbody graft, made of allograft bone and/or a synthetic material (e.g., plastic or titanium) directly into the disc space. When the surgical approach for this type of procedure is from the back it is called a posterior lumbar interbody fusion (PLIF).
In a typical PLIF procedure, the spine is approached through an incision in the midline of the back and the left and right lower back muscles (erector spinae) are stripped off the lamina on both sides and at multiple levels. After the spine is approached, the lamina is removed (laminectomy) which allows visualization of the nerve roots. The facet joints, which are directly over the nerve roots may then be undercut (trimmed) to give the nerve roots more room. The nerve roots are then retracted to one side and the disc space is cleaned of the disc material.
A spacer packed with bone graft material is then inserted into the disc space to promote bone growth between the adjacent vertebrae, allowing them to heal as a single structure.
Presently known endoscopic techniques involve inserting the interbody graft directly into the space between the vertebrae, while holding the nerves and dura out of the way. Specifically, the surgeon screws a handle into the spacer, forces the spacer between the vertebrae and hammers it down to a desired depth, then unscrews and removes the handle from the spacer. This approach is cumbersome, and tends to irritate to the surrounding nerves and dura.
Methods and apparatus are thus needed which overcome these and other limitations of the prior art.
Various features and characteristics will also become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background section.